Gas-responsive signal actuator



April 2, 1957 w. H. Rosr-:NBLUM Er Ax.

GAS-RESPONSIVE SIGNAL ACTUATOR Fviled June 13, 1955 2 Sheets-Sheet l 3 Y?. 24 gg t l5 f-i7 w f INVENTORS B I+ MPM GAS-RESPONSIVE SIGNAL ACTUATOR 2 Sheets-Sheet 2 Filed June l3, 1955 United -States Patent GAS-RESPONSIVE SIGNAL ACTUATOR William H. Rosenblum, Brooklyn, and lliax Mirkln, Bronx, N. Y.

Application June 13, 1955, Serial No. 514,888

8 Claims. (Cl. 340-237) This invention relates to gas-responsive signal actuator, and more particularly one utilizing sensitivity of a photocell and an electric circuit therewith to incite a signal when a certain gas under scrutiny reaches a denite proportion of concentration.

In its general aspect, the invention is directed to detection of a maximum allowable proportion of a poisonous gas in a room or enclosure occupied by humans and to give an alarm.

More specifically, the invention is directed to the detection of a maximum allowable proportion of carbonmonoxide in such enclosure.

In greater detail, the invention utilizes color change of a composition caused by reaction of said gas, to effect a variation in light directed on a photocell and to ultimately incite the signal.

VA further object of the invention is to incorporate said composition in the apparatus in the form of a replaceable pellet.

Another object of the invention is to provide a readily portable apparatus contained as a complete unit and adapted to be plugged-in wherever current is available and detection of the gas is desired.

Still further objects, advantages and novelty of conf4 struction will appear to persons skilled in the art to ywhich the invention appertains, as the description proceeds, both by direct. recitation thereof and by implication from the context.

Referring to the accompanying drawings, in which like numerals of reference indicate similar parts throughout the several views:

Figure `l isa perspective VView of an apparatus embodying our invention and shown with a removable plate and pellet holder;

, Figure 2 is a face view of said plate removed from its associated position with the apparatus housing;

Figure 3 is a sectional view on line III- Ill of Fig. 2;

Figure 4 is a sectional view similar to Fig. 3 but showing the pellet permanently encased with replaceable only as a complete entity;

Figure 5 is a ysectional view showing the holder to be a permanent part of the apparatus housing, and the pellet and its encasement removable as an entity therefrom; and

Figure 6 is a View partially in section and partially diagrammatic showing interior construction and one circuit arrangement illustrative of the invention.

, In the specific embodiment of the invention illustrated in said drawings, the reference numeral 10 designates the apparatus housing here shown as a rectangular box with an electric bell 11 thereon exemplary of a signal, preferably audible, which is to be operated in use of the apparatus. At what will be termed herein the front end of said housing isa slidably removable plate 12 carried in a slideway 13 on the yfront end wall14 of said housing. In said plate is a hole 15 which is conveniently circular and opensto the linterior of said housing, the front end wall being cut away behind said plate at least to the extent of said hole in juxtaposition thereto. In Figures 1, 2 and 3, said hole is shown as bordered by an outwardly projecting collar 1S soldered or otherwise held in place. Removably mounted in and projecting forwardly from said collar 1S is a capsule 19 constituting a feature of the present invention. The detail construe` tion of said capsule, especially as to its encasement or shell may be considerably varied, as will be apparent from a comparison of Figs. 3, 4 and 5. Also the mounting of said capsule in place is subject to various embodiments agreeable to the construction of the capsule.

The essentials of said capsule, common to all forms thereof, comprise an encasement open at both ends and containing certain laminations more specifically defined hereinafter, the inner one of said laminations being exposed to the interior of the apparatus housing and the outer one exposed to the exterior atmosphere. The specific showing of the capsule illustrated in Figures l, 2 and 3 will now be described in detail.

The capsule of Figs. l, 2 and 3 comprises an encasement 20 in the form of an annular shell of appropriate diameter to t within and have screw-threaded engagement, as at 21, with the aforementioned collar 18 for mounting and retaining purposes. The inner end of said collar is shown provided with a radially inward peripheral tiange 22 located in opposition to the inner end of said shell and thereby constituting means for retaining a first or inner lamination 23 which is transparent, such as a thin glass disc, and sufficiently rigid to retain a second lamination 24, hereinafter referred to as the color-changing lamination, in turn backed by a third lamination 25 pervious to the gas with which the apparatus is to function, said third lamination being retained by a fourth lamination or foraminous retainer 26 which may conveniently consist of a fabric or other net. A plug 27 having a longitudinal hollow 28 therethrough is screw-threaded into the outer end of said annular shell and bears at its inner` end against the peripheral margin of said fourth lamination or retainer 26 and adequate pressure is applied to cause the color-changing lamination to engage against the transparent lamination throughout the juxtaposed surfaces thereof. By removal of said plug, the several laminations up to the glass or firstinsert the other laminations and return the plug intoplace.

As indicated above, the invention is susceptible to def tail variationsin construction, and in Fig. 4 a modification of encasernent structure is illustrated. A plate 12 with a hole l5 is again employed, but in this instance the encasement, here designated by numeral Ztla permanently retains the several laminations 23 to 2.6 inclusive, they being loaded in the encasernent at the factory. In this instance, the encasement is shown as provided with an outwardly or radially projecting flange 3d which may be brought into ilatwise engagement with the inner face of the plate next to or marginally of said hole. Said flange also projects radially inward suticiently to engage the marginal periphery of the lirst or glass lamination 23. Coaxial with the flange, said engagement provides a projecting collar 3i circumferentially.around the edge of the glass disc or iirst lamination 23, with the peripheral outer face of said collar fitting the hole andheld therein by friction or otherwise. Said encasement may `also heprovided with a peripheral shoulder 32 around.

the rim of the outward face of the glass disc 23 and for- Patented Apr. 2, 1957- wardly thereof may curlu onward toward the axis somewhat formingA a partial dome forV retaining the `other' laminations and obtaining tight contact of the juxtaposed surfaces of the color-changing lamination 24 with the first` or transparent lamination 23. Thus a permanent capsule is provided which may be exchanged as a unit for another.

While the foregoing description has indicated Ithat the capsule is mounted on a removable plate, it is to be understood that it may be mounted directly upon the end wall of the housing, such construction being shown in Figs. 5 and 6.

According to the showing in. Figures 5 i and 6, the hole in the end wall 1411 is provided with an outwardly projecting collar 18]) adapted to receive and frictionally or otherwise retain a unitary capsule 19h therein. Said capsule is shouldered at 33 for seating engagement against the outer edge of said collar for limiting inward insertion of said capsule into said collar. The encasement or shell 2Gb of this capsule is cylindrical, and provides a press or snap t for retention of the glass disc or rst lamination 23 and is shown with an enlarged hollow 34 at its outer end for reception of the rim of the foraminous lamination 26 which may be suitably retained therein, for instance by use of an adhesive. The color changing lamination 24 is located in close juxtaposition to the transparent lamination 23 and is held thereagainst by the pervious lamination 25 interposed between said colorchanging lamination and said foraminous lamination. This again provides a unitary capsule which may be removed as an entity and replaced by another.

One example of colorchanging lamination consists of a silica gel impregnated with ammonium molybdate, sulfurie acid and palladium chloride. A yellow silicomolybdate complex, Hg(Si(MosOr)e) is formed. r[his material is generally known as a colorimetric indicator gel, and may be purchased from such concerns as Mine Safety Appliances Co. of Long Island City, New York, and United States Safety Service Co. of Kansas City, Missouri. The third or gas-permeable lamination 25 may also be a silica gel, but without impregnation with the color-changing complex. The gel of both of these laminations 24 and 25 will become permeated with carbon-monoxide if present in the atmosphere, and the impregnated complex will turn from yellow to green, the depth or darkness of the green color increasing in proportion to increase in the presence of the carbon-monoxide. Thus, when the atmosphere in which the apparatus is placed is charged dangerously with carbon-monoxide,`

that gas will permeate the gel laminations 24 and 25 `and the transparent lamination 23 will then be backed by a green surface instead of a yellow surface. The darker the green, the less reflective it will be of light, and we take advantage of that fact for -timely operation of the audible signal 11.

Referring to Fig. 6, it will be observed that within housing there is a constantly illuminated electric light bulb 3S. This bulb is shown provided with a shield 36 i which directs the light as a beam the axis of which is oblique to the surface of the color-changing lamination and directed to impinge on said surface. The angle of incidence and the angle of reflection of the light beam are of course equal and opposite, and interposed to the reflected beam on the axis of retlection is a photocell 37. Maximum reflection of light to the photocell occurs while said color-changing lamination has its normal color of yellow and the photocell then has its maximum conductivity, but that `conductivity decreases as the light lessens due to change of the reilecting surface from yellow to green and with the shade of green deepening.

A suitable circuit is employed to make the reduced conductivity of the photocell effective upon signal 11. As'here shown, a thyratron 38 has a cut-otl grid 39 therein between a cathode 40 and an anode 41, said grid being charged negatively from the photocell, and of 4 course the negative charge on said grid is greatest when the photocell is mostconductiveV and that is when the color-changing lamination is yellow. The negative charge on grid 39 interrupts passage of electrons, and thus no current is derived from the thyratron. The negative charge on grid 39 is, however, variable and becomes less as the change of light reflection to the photocell lessens the conductivity of the photocell.` Also within the thyratron is a second grid 42 having a constant positive bias applied thereto. As the cut-oil grid 39 becomes less and less negative, a, value is reached when` the positive charge of the second grid 42 isV more effective on the electrons than the negative charge of grid 39 and a flow of electrons from the cathode to the anode consequently takes place and current passes. The output of the thyratron is applied to a magnet 43 of a relay switch 44 which closes the circuit to a bell-transformer primary 45, the secondary 46 of which is connected to bell or signal 11.

Peek-holes 47 and 48 may be provided in the housing l() in appropriate relation to the light bulb 35 and to the thyratron 38 respectively so that the user may make inspection from time to time to see to it that the laments of both are lit.

We claim:

l. A gas-responsive signal actuator constructed as a portable unit and comprising a plurality of laminations of which one is foraminous and another spaced therefrom is transparent and an intermediate one has a first surface thereof toward the foraminous lamination and its opposite surface toward the transparent lamination, said intermediate lamination having more than paper-thin thickness and comprising a body of color-changing material wherein one color is more reilective of light than another color which said material may change from and to, gas affecting the intermediate lamination being required to seep through the body thickness of said intermediate lamination to change the color of said second surface toward the transparent lamination, means for applying a constant beam of light to said second surface, a photocell in the path of the reilected beam of light from said second surface, the conductivity of said photocell being variable in response to variation of light reflected thereto, and a signal connected with said photocell.

2. A gas-responsive signal actuator in accordance with claim l, wherein said signal is audible and is sounded only after gas has seeped through the body thickness of said intermediate lamination and a predetermined color change has transpired in said material at said second sur face toward the transparent lamination.

3. A gas-responsive signal actuator in accordance with claim l, wherein said color-changing material is included as a lamination within a capsule.

4. A gas-responsive signal actuator in accordance with claim l, wherein a housing is provided containing said means and said photocell, and wherein said color-changing material is mounted exterior to said housing, said housing having a hole through which the incident and reflected beam of light may pass to and from said surface of said material.

5. A gas-responsive signal actuator in accordance with claim 3, wherein said color-changing material is replaceable.

6. A gas-responsive signal actuator in accordance with claim 3, wherein said capsule is replaceable.

7. A gas-responsive signal actuator in accordance with claim l, wherein a housing is provided containing and shielding said photocell, said housing having means for mounting and retaining said laminations n immobile relation to said photocell in use whereby rellection of light to said cell occurs from a surface that is standing still.

8. A gas-responsive signal actuator, comprising a unitary capsule of substances retained in given relation to each other in any position of said capsule, said substances comprising respectively a foraminous one and a trans parent one substantially parallel to each other, and an intermediate one retained substantially fixed between the foraminous one and transparent one, said intermediate one being formed at least in part of color-changing material and of a character that the color changes under influence of a gas admitted through said foraminous substance.

References Cited in the le of this patent UNTED STATES PATENTS Johnson Apr. 11, 1939 Moses et al. Feb. 18, 1941 Sundstrom et a1 May 19, 1953 

